Facilitative interactions among aquatic invaders: is an "invasional meltdown" occurring in the Great Lakes?

2001 ◽  
Vol 58 (12) ◽  
pp. 2513-2525 ◽  
Author(s):  
Anthony Ricciardi
Keyword(s):  
Great Lakes ◽  
Introduced Species ◽  
Biotic Resistance ◽  
Past Century ◽  
Theoretical Argument ◽  
Cumulative Number ◽  
Invasional Meltdown ◽  
Species Introductions ◽  
Facilitative Interactions ◽  
The Impact

A widely cited hypothesis in ecology is that species-rich communities are less vulnerable to invasion than species-poor ones, owing to competition for limiting resources (the "biotic resistance" model). However, evidence for biotic resistance in aquatic ecosystems is equivocal. Contrary to the view that communities become more resistant to invasion as they accumulate species, the rate of invasion has increased over the past century in areas that have received frequent shipping traffic. Furthermore, introduced species may facilitate, rather than compete with, one another. A review of invasions in the Great Lakes indicates that direct positive (mutualistic and commensal) interactions among introduced species are more common than purely negative (competitive and amensal) interactions. In addition, many exploitative (e.g., predator–prey) interactions appear to be strongly asymmetric in benefiting one invading species at a negligible cost to another. These observations, combined with an increasing invasion rate in the Great Lakes, tentatively support the Simberloff – Von Holle "invasional meltdown" model. The model posits that ecosystems become more easily invaded as the cumulative number of species introductions increases, and that facilitative interactions can exacerbate the impact of invaders. It provides a theoretical argument for substantially reducing the rate of species introductions to the Great Lakes.

scholarly journals Diet composition of the invasive red-whiskered bulbul Pycnonotus jocosus in Mauritius

2010 ◽  
Vol 26 (3) ◽  
pp. 347-350 ◽  
Author(s):  
Jannie Fries Linnebjerg ◽  
Dennis M. Hansen ◽  
Nancy Bunbury ◽  
Jens M. Olesen
Keyword(s):  
Invasive Species ◽  
Introduced Species ◽  
Native Species ◽  
Diet Composition ◽  
Ecological Perspective ◽  
Positive Interactions ◽  
Invasional Meltdown ◽  
Ecological Processes ◽  
Successful Establishment ◽  
The Impact

Disruption of ecosystems is one of the biggest threats posed by invasive species (Mack et al. 2000). Thus, one of the most important challenges is to understand the impact of exotic species on native species and habitats (e.g. Jones 2008). The probability that entire ‘invasive communities’ will develop increases as more species establish in new areas (Bourgeois et al. 2005). For example, introduced species may act in concert, facilitating one another's invasion, and increasing the likelihood of successful establishment, spread and impact. Simberloff & Von Holle (1999) introduced the term ‘invasional meltdown’ for this process, which has received widespread attention since (e.g. O'Dowd 2003, Richardson et al. 2000, Simberloff 2006). Positive interactions among introduced species are relatively common, but few have been studied in detail (Traveset & Richardson 2006). Examples include introduced insects and birds that pollinate and disperse exotic plants, thereby facilitating the spread of these species into non-invaded habitats (Goulson 2003, Mandon-Dalger et al. 2004, Simberloff & Von Holle 1999). From a more general ecological perspective, the study of interactions involving introduced and invasive species can contribute to our knowledge of ecological processes – for example, community assembly and indirect interactions.

scholarly journals Biotic resistance or invasional meltdown? Diversity reduces invasibility but not exotic dominance in southern California epibenthic communities

2021 ◽  
Author(s):  
Ryan Amir Beshai ◽  
Danny Truong ◽  
Amy Henry ◽  
Cascade Sorte
Keyword(s):  
Community Development ◽  
Exotic Species ◽  
Community Assembly ◽  
Southern California ◽  
Biotic Resistance ◽  
Community Diversity ◽  
Fouling Communities ◽  
Invasional Meltdown ◽  
Facilitative Interactions ◽  
Over Time

Abstract High community diversity may either prevent or promote the establishment of exotic species. The biotic resistance hypothesis holds that species-rich communities are more resistant to invasion than species-poor communities due to greater interspecific competition. Conversely, the invasional meltdown hypothesis proposes that greater exotic diversity increases invasibility via facilitative interactions between exotic species. To evaluate the degree to which biotic resistance or invasional meltdown influences marine community structure during the assembly period, we studied the development of marine epibenthic “fouling” communities at two southern California harbors. We found that fewer exotic species established as total and exotic richness increased during community assembly and that this effect remained after accounting for space availability. We also found that changes in exotic abundance decreased over time. Throughout the assembly period, gains in exotic abundance were greatest when space was abundant and richness was low. Altogether, we found greater support for biotic resistance than invasional meltdown, suggesting that both native and exotic species contribute to biotic resistance during early community development. However, this resistance may not reduce the total dominance of exotic species.

scholarly journals A Long-Term Fine-Resolution Record of AVHRR Surface Temperatures for the Laurentian Great Lakes

2018 ◽  
Vol 10 (8) ◽  
pp. 1210
Author(s):  
Charles White ◽  
Andrew Heidinger ◽  
Steven Ackerman ◽  
Peter McIntyre
Keyword(s):  
Great Lakes ◽  
Morphological Characteristics ◽  
Laurentian Great Lakes ◽  
Environmental Research ◽  
Weighted Interpolation ◽  
Large Lakes ◽  
Fine Resolution ◽  
Observation Times ◽  
The Impact

Inland waters are warming at highly variable rates that often differ from regional air temperature trends. This variable warming is partially attributable to an individual lake’s geographical and morphological characteristics. In very large lakes, significant intralake variability in long-term warming trends has also been observed. In light of this intralake and interlake heterogeneity of lake surface water temperature (LSWT) and LSWT trends, we revisit the 1.1 km Advanced Very High Resolution Radiometer (AVHRR) record for the Laurentian Great Lakes. In this work, we have assembled a long-term (1986–2016) and high-spatial-resolution (0.018°) daily LSWT dataset using AVHRR record. Subtracting an empirically-determined mean diurnal cycle mitigates the effects of varying observation times. Adjustments in the georegistration of the images are made to reduce the impact of AVHRR navigational errors on the earlier platforms. Both the original daily composites, and a gap-filled product using locally weighted interpolation methods will be made available to support fine-scale physical and environmental research in the region.

Introducing a new dataset on leadership change in rebel groups, 1946–2010

2018 ◽  
Vol 56 (2) ◽  
pp. 306-315 ◽  
Author(s):  
Carmela Lutmar ◽  
Lesley G Terris
Keyword(s):  
Civil War ◽  
Future Research ◽  
Theoretical Argument ◽  
War And Peace ◽  
Leadership Change ◽  
Rebel Groups ◽  
Interstate Disputes ◽  
Leadership Changes ◽  
The Impact ◽  
Qualitative Literature

Leaders and leadership changes are found to influence states’ foreign policy decisions, in particular with respect to war and peace between states. Although this issue is also addressed in the qualitative literature on intrastate wars, the influence of leadership turnovers in civil war has received limited systematic attention. One reason for this is the scarcity of quantitative data on rebel group leaderships. To fill this gap, we present a comprehensive dataset on leadership changes in rebel groups, 1946–2010, organized by rebel-month. The effects of leadership changes among parties engaged in civil war are argued to be more complex than those found in interstate disputes. In this article we present our theoretical argument followed by presentation of the variables in the dataset and descriptive statistics. To demonstrate the potential research value of the dataset we examine the impact of leader shifts on civil war settlement in Africa. We conclude with avenues for future research which might benefit from this dataset.

scholarly journals The Impact of Armed Conflict on the Epidemiological Situation of COVID-19 in Libya, Syria and Yemen

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohamed A. Daw
Keyword(s):  
Armed Conflict ◽  
Early Stage ◽  
Armed Conflicts ◽  
Cumulative Number ◽  
The Novel ◽  
Global Pandemic ◽  
Large Numbers ◽  
Public Data ◽  
Novel Coronavirus ◽  
The Impact

Background: Since the Arab uprising in 2011, Libya, Syria and Yemen have gone through major internal armed conflicts. This resulted in large numbers of deaths, injuries, and population displacements, with collapse of the healthcare systems. Furthermore, the situation was complicated by the emergence of COVID-19 as a global pandemic, which made the populations of these countries struggle under unusual conditions to deal with both the pandemic and the ongoing wars. This study aimed to determine the impact of the armed conflicts on the epidemiology of the novel coronavirus (SARS-CoV-2) within these war-torn countries and highlight the strategies needed to combat the spread of the pandemic and its consequences.Methods: Official and public data concerning the dynamics of the armed conflicts and the spread of SARS-COV-2 in Libya, Syria and Yemen were collected from all available sources, starting from the emergence of COVID-19 in each country until the end of December 2020. Datasets were analyzed by a set of statistical techniques and the weekly resolved data were used to probe the link between the intensity levels of the conflict and the prevalence of COVID-19.Results: The data indicated that there was an increase in the intensity of the violence at an early stage from March to August 2020, when it approximately doubled in the three countries, particularly in Libya. During that period, few cases of COVID-19 were reported, ranging from 5 to 53 cases/day. From September to December 2020, a significant decline in the intensity of the armed conflicts was accompanied by steep upsurges in the rate of COVID-19 cases, which reached up to 500 cases/day. The accumulative cases vary from one country to another during the armed conflict. The highest cumulative number of cases were reported in Libya, Syria and Yemen.Conclusions: Our analysis demonstrates that the armed conflict provided an opportunity for SARS-CoV-2 to spread. The early weeks of the pandemic coincided with the most intense period of the armed conflicts, and few cases were officially reported. This indicates undercounting and hidden spread during the early stage of the pandemic. The pandemic then spread dramatically as the armed conflict declined, reaching its greatest spread by December 2020. Full-blown transmission of the COVID-19 pandemic in these countries is expected. Therefore, urgent national and international strategies should be implemented to combat the pandemic and its consequences.

scholarly journals The physiological reaction in the local breed and introduced silkworm breeds on the difference in conditions of detention of the wintering eggs

2021 ◽  
Vol 210 (07) ◽  
pp. 35-46
Author(s):  
Gyul'nar Bagirova ◽  
Hokuma Kulieva
Keyword(s):  
Aqueous Solutions ◽  
Introduced Species ◽  
Strong Response ◽  
Local Breed ◽  
Physiological Reaction ◽  
Content Selection ◽  
Local Species ◽  
The Difference ◽  
The Impact ◽  
Positive Effect

Abstract. The purpose of this study is the ascertainment of to the physiological responses to exogenous exposure to aqueous solutions of the drug “Violet-K” (C24H28N3Cl) in the phase of wintering eggs of the local and introduced silkworm species. Methods. The research was carried out according to the methodology developed by us for the content, selection and processing of material [9], [10]. Statistical analysis was performed according to G. F. Lakin [11]. Results. It was found that in the absence of sharp fluctuations of the temperature and air humidity, the effect of exposure to water and 0.01% and 0.001 % aqueous solutions of the “Violet-K” preparation on hibernating eggs causes a response of caterpillars at younger ages during molting, by the fifth age this effect diminishes. A strong response to the impact in terms of weight of caterpillars was revealed for the introduced silkworm species: against the background of minor fluctuations in the “Oragase” variant for caterpillars “Sverico-sari” the difference with the control by age is 16,4 % (III), 143,3 % (IV) and 27,3 % (V). The introduced species “Oragase” often differs from the “Sverico-sari” and the local breed “Veten” by the presence of negative responses: the weight of caterpillars after exposure compared to the control corresponds to + 43.7 % (III), + 65.0 % (IV), –36.2 % (V). It was found that the content of wintering grains in water and aqueous solutions of the “Violet-K” preparation leads to the weight increase of the silk shell: by 54.4–80.5 % (p < 0.05 and 0.001) in the local species, as well as by 11.4–16.1 % (0.001 %) and 2.7 % (0.01 % solution “Violet K”) p < 0.05 and 0.001. The species “Oragase” differs in this effect compared with the control, particularly, in the comparison with control, the impact promotes to a significant decrease in the weight of the silk shell by 33 % (–78.5 mg) and 22.5 % (–49.0 mg), p < 0.001. The impact is reflected in the date of departure of butterflies and the number of laid eggs, and only in introduced species: the positive effect compared to the control, on average on 1 female was 3.6–4.8 times higher (“Sverico-sari”) and 1.1 times (“Oragase”).

scholarly journals Le port de Montréal à la veille de l’ouverture de la nouvelle voie navigable du Saint-Laurent

2005 ◽  
Vol 3 (5) ◽  
pp. 85-95
Author(s):  
Pierre Camu
Keyword(s):  
Great Lakes ◽  
Traffic Congestion ◽  
Royal Commission ◽  
Different Types ◽  
Mcgill University ◽  
General Cargo ◽  
The Impact

A few months before the opening of the new St. Lawrence Seaway, the author reappraises the effects of the Project on the Port of Montréal. Analysing the conclusions and recommendations of three studies published in 1957 and 1958, the Report of the ToIIs Committee of the St. Lawrence Seaway, the Report of the Royal Commission on Coastal Trade, and the report published by the Faculty of Commerce of McGill University, The Impact of the St. Lawrence Seaway on the Montréal Area, one comes to the conclusion that the Port of Montréal will remain a grain transhipment centre, but will lose a good part of its general cargo trade to Great Lakes ports. The loss of general cargo tonnage is estimated at 650,000 tons. In conclusion, several factors that may contribute to keep Montréal the leading oceanic port on the Seaway are stressed : 1. the imponderables ; 2. the Lachine rapids that are reduced in size by the new canal, but do not disappear; 3. competition between different types of vessels ; and, 4. traffic congestion in the waterway.

scholarly journals Convective environment in pre-monsoon and monsoon conditions over the Indian subcontinent: the impact of surface forcing

2018 ◽  
Vol 18 (10) ◽  
pp. 7473-7488 ◽  
Author(s):  
Lois Thomas ◽  
Neelam Malap ◽  
Wojciech W. Grabowski ◽  
Kundan Dani ◽  
Thara V. Prabha
Keyword(s):  
Indian Subcontinent ◽  
High Surface ◽  
Convective Available Potential Energy ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Tropospheric Temperature ◽  
Theoretical Argument ◽  
Near Surface ◽  
Surface Moisture ◽  
The Impact

Abstract. Thermodynamic soundings for pre-monsoon and monsoon seasons from the Indian subcontinent are analysed to document differences between convective environments. The pre-monsoon environment features more variability for both near-surface moisture and free-tropospheric temperature and moisture profiles. As a result, the level of neutral buoyancy (LNB) and pseudo-adiabatic convective available potential energy (CAPE) vary more for the pre-monsoon environment. Pre-monsoon soundings also feature higher lifting condensation levels (LCLs). LCL heights are shown to depend on the availability of surface moisture, with low LCLs corresponding to high surface humidity, arguably because of the availability of soil moisture. A simple theoretical argument is developed and showed to mimic the observed relationship between LCLs and surface moisture. We argue that the key element is the partitioning of surface energy flux into its sensible and latent components, that is, the surface Bowen ratio, and the way the Bowen ratio affects surface buoyancy flux. We support our argument with observations of changes in the Bowen ratio and LCL height around the monsoon onset, and with idealized simulations of cloud fields driven by surface heat fluxes with different Bowen ratios.

How direct and indirect non-native interactions can promote plant invasions, lead to invasional meltdown and inform management decisions.

2020 ◽  
pp. 153-176
Author(s):  
Sara E. Kuebbing
Keyword(s):  
Native Species ◽  
Native Plants ◽  
Full Range ◽  
Invasion Biology ◽  
Apparent Competition ◽  
Indirect Interactions ◽  
Competitive Interactions ◽  
Invasional Meltdown ◽  
Soil Microbial ◽  
Facilitative Interactions

Abstract In 1999, Daniel Simberloff and Betsy Von Holle introduced the term 'invasional meltdown'. The term and the concept have been embraced and critiqued but have taken a firm hold within the invasion biology canon. The original formulation of the concept argued two key points: first, biologists rarely study how non-natives interact with one another. Second, nearly all the conceptual models about the success and impact of invasive species are predicated on the importance of competitive interactions and an implicit assumption that non-natives should interfere with establishment, spread and impact of other non-natives. In response, Simberloff and Von Holle called for more research on invader interactions and proposed an alternative consequence of non-native species interactions - invasional meltdown - where facilitative interactions among non-natives could increase the invasion rate or ecological impacts in invaded systems. This chapter outlines the primary pathways in which direct and indirect interactions among non-natives could lead to invasional meltdown. It provides examples of how different types of interactions among non-natives could lead to net positive effects on the invasion success of non-native plants or the impact of non-native plants on invaded ecosystems. Direct effects are by far the most commonly explored form of non-native- non- native interaction, primarily focusing on plant mutualisms with pollinators, seed dispersers or soil microbial mutualists. There are, however, also examples of non-native plants that benefit from commensal and even herbivorous interactions with other non-natives. Indirect interactions among non-natives are very infrequently studied. Although examples are scarce, non-natives may indirectly benefit other non-native plants through trophic cascades, apparent competition and indirect mutualisms. It remains unclear whether indirect effects are important pathways to invasional meltdown. More work is needed on studying ecosystems that are invaded by multiple non-native species and we need to consider the full range of interactions among non-natives that could either stymie or promote their spread, population growth and impact. Only then can we address how common facilitative interactions are relative to competitive interactions among non-natives or provide robust suggestions on how to manage ecosystems.

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